Alternating-current apparatus.



No. 781,932. PATENTED FEB. 7, 1905. E. BENNETT.

ALTBRNATING CURRENT APPARATUS.

APPLICATION FILED 0OT.13, 1902.

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WITNESSES: 2 INVENTOH 1 4, W TTUR NEY.

Patented February 7, 1905.

NITED STATES PATENT OFFICE.

EDNVARD BENNETT, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO GEORGE TESTINGHOUSE, OF PITlSBURG, PENNSYLVANIA.

ALTERNATlNG-CURRENT APPARATUS.

SPECIFICATION forming part of Letters Patent N0. 781,932, dated February 7, 1905.

Application filed October 13,1902. Serial No. 127,138.

To a who? it puny concern:

Be it known that I, EDWARD BENNETT, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Alternating-Current A pparatus, of which the following is a specification.

My invention relates to apparatus comprising a magnetizing-winding and a member movable through a limited distance to a given position by the magnetic field produced by currents in such winding, and has particular reference to cut-outs for the heaters of electric lamps of the type in which the glower is a non-conductor except when heated to a high temperature, but is not necessarily restricted to such service.

The object of my invention is to provide apparatus of the character above indicated which shall be free from the humming noise caused by invisible vibrations of its various parts under the magnetic stresses alternately applied and relieved by alternating currents under usual conditions and also to substantially eliminate vibratory movements of the movable member of the apparatus with reference to its support.

My invention is illustrated in the accompanying drawings, in which Figure 1 is a diagram showing minimum and maximum currents and corresponding waves of induction in apparatus constructed and operated in accordance with my invention; and Fig. 2 is a view, partially in side elevation and partially in section, of my invention as embodied in a heater cutout for electric lamps.

As already stated, the invention is not restricted to use in electric-lamp cut-outs; but for convenience it will be described with reference to this specific utilization, other uses which would fall within the scope of my invention being-susceptible of ready understanding without specific enumeration or description.

In the heater-eut-out coils of electriclamps of the type above mentioned the current varies between wide limits, because the lamp must sometimes operate on a low voltage and with one or more glowers burned out, and since it is desirable to have the movable terminal of the-cut-out coil actuated by the minimum current corresponding to the low voltage and the inoperative glowors and the coil mustalso carry the maximum current corresponding to the proper voltage and with all the glowers operative it follows thata large degree o't'fiuctuation in the magnetic pull upon the movablemember of the cut-out may obtain in a lamp having a cut-out of usual construction and characteristics. In a three-glower lamp, for example, the cut-out coil may be called upon to operate between .Q L and 1.2 amperes-that is, the moving members of the cut-outs must be separated from the stationary contact-terminals by the action of a current which is only one-fifth of that which the glowers normally take. By my present invention I propose to so proportion the iron parts of the magnetic circuit with reference to the air-gap that the portion of the former which supplies the greatest percentage of lines of force (for example, the core) will be saturated at or below the minimum current. If such relation be secured, there will be practically no increase in induction when the apparatus is operated at currents above the minimum. This is a desirable condition, since any increase in induction above that which is sutlicient to move and hold the movable member of the cutout causes increased stresses that are productive of noise. For example, if two cut-outsare so proportioned that their cores respectively become saturated at a minimum and at a maximum current when the cut-outs are operating under the maximum current, which according to the example above given would be five times the minimum, the induction of the one will be live times that of the other, and the pull of the respective armatures and the other stresses in various parts, which vary as the square of the induction, will be in the ratio of twenty-live to one.

The embodiment of my invention illustrated in Fig. 2 of the drawings comprises a coil 1, having a core 2 mounted upon a suitable base 3 and also provided at its bottom with an extended and bent pole-piece L and at its top with a magnetizable bar or plate 5, which serves as a conductor of the lines of force and as a support for the pivoted armature 6, the latter cooperating with a stationary contactterminal 7 to complete the heater-circuit when the magnet is deenergized.

The usual members and circuits of a lamp having three glowers that are non-conducting at ordinary temperatures are also shown as follows: One side, 8, of the lamp-circuit is connected to corresponding terminals of the glowers 9 through the coil 1, and a ballast 10 and the other side, 11, of the lamp-circuit is connected to corresponding terminals of the glowers 9 and the heater 12, the other terminal of the heater being connected to the conductor 8 through the contact-terminal 7, the armature 6, and the bar 5. When the glower is heated to conductivity, the magnet will obviously withdraw the armature 6 from the terminal 7, and thus break the heater-circuit. The illustration of lamp parts is not intended to limit the invention to any specific number, form, or arrangement of such parts, except in so far as limitations are imposed by service conditions.

In Fig. l the curve 0 represents the minimum current and curve 0 the maximum current, the curve n the induction produced by the minimum current, n the induction produced by the maximum current, and n a square-top wave, which the curve of closely approximates, these values being such as are present when the core or some portion of the magnetic circuit is saturated at or below the m1n1mum current. With a flat-top wave, as represented by the curve 71 there is substantially no tendency for the moving member of the cut-out to vibrate with any appreciable amplitude, since this wave very closely approximates the square-top wave, and the latter is identical in effect with direct current so far as the production of vibratory movement of the armature is concerned.

I make no claim herein to the structural features of the cut-out device shown and described, such features being essential to my invention only to the extent that they provide a magnetic circuit at least a portion of which is saturated by the minimum current of the circuit in connection with which the device is used.

I claim as my invention 1. The combination with a current-using means of variable receptivity,of a cut-out having a coil in series with said means and a movable armature therefor that serves to close a shunt around said coil and current-using means when the coil is deenergized, the magnetic circuit of said coil or a portion thereof being saturated by the minimum current taken by the current-using means.

2. In an electric glower-lamp, the combination with one or more glowers and a heater connected in shunt thereto, of a cut-out for the heater having an actuating-coil connected in series relation with the glower or glowers and having a magnetic circuit at least a portion of which is saturated by the minimum current taken by the glower or glowers.

3. In an electric glower-lamp, the combination with a plurality of glowers and a heater connected in shunt thereto, of a cut-out for said heater having an actuating-coil connected in series relation with said glowers and having a magnetic circuit at least a portion of which is saturated by the current taken by a single glower.

&. The combination with a current-using means of variable resistance and .a currentusing means of substantially invariable resistance in shunt thereto, of a cut-out for the shunt-circuit having a coil in series with the variable-resistance means and, having a magnetic circuit at least a portion of which is saturated by the minimum current taken by said variable-resistance means.

5. In an electric glower-lamp, the combination with one or more glowers adapted to utilize difierent amounts of current and a heater connected in shunt thereto, of a cutout for said heater having a coil connected in series with said glower or glowers and having a magnetic circuit at least a portion of which is saturated by the minimum current taken by said glower or glowers.

In testimony whereof I have hereunto subscribed my name this Lth day of October, 1902.

EDWARD BENNETT.

Witnesses:

IVIARSHALL WILFRED HANKS, J AMES B. YOUNG. 

